Cholesterol Assimilation of Two Probiotic Strains of Lactobacillus caseiused as Dairy Starter Cultures

Consumption of milks fermented with lactic acid bacteria has been shown to improve lipid profiles; however, the mechanisms underlying this improvement are not clear. Using in vitroanalyses, the aim of this study was to investigate how Lactobacillus caseistrains AP and AG assimilate cholesterol.

Bacterial growth in ox gall-supplemented media, quantity of assimilated cholesterol and activity of bile salt hydrolase were assessed in Lactobacillus casei strains AP and AG. Furthermore, cholesterol attachment to cell walls was assessed using scanning electron microscopy.

LactobacilluscaseiAG showed a higher cholesterol assimilation (13.05 mgdl-1±0.48)than LactobacilluscaseiAP (8.05 mgdl-1 ±0.48) as well as a faster growth rate of the former strain thanthat of the latter one. Growth inhibition of Lactobacillus caseiAP was associated with increased activity of bile salt hydrolase (halo size of 1.62 mm ±0.20), compared to that of Lactobacillus caseiAG (1.37 mm±0.07) and upregulation of the bshgene. High cholesterol assimilations by Lactobacillus caseiAG seem to attribute to membrane attachment via resistance to bile acids.